Valve-gear oe steam-engines



'j VALVE-GEAR or srEAMfENGINEs;

Specification of Letters Patent No. 32,534, dated June 11, 1861.

To all whom it may concern: j

Be it known that I, J. R. ROBINSON, of Boston, in the county of Suffolk and State of Massachusetts, have invented certain new and useful Improvements in the Valve-Gear of Steam-Engines; and I do hereby declare that the following" is a full, clear, andexact description of the same,refere1`1cebeing had to the accompanying drawing, forming part of this speciicatiOn, in which- ,Figure l,v is aside elevation of a horizontal engine with my invention applied. Fig. 2, is a plan of the same with the valve chest and valves in section. Fig. 3, is a diagram.

illustrating the `action of a portion of the valve gear. ig.` 4, illustrates a modiiica-` tion of my invention. v W Y Similar characters of reference indicate corresponding'parts in the severaligures.

j My invention consists inthe employment of two eccentrics, connected by a link `for the purpose ofclosing the parts to cut olil steam from the cylinder` at various `points in the stroke of the piston, in combination with in dependent. means of opening the ports for the induction of the steam.` l

It also consists in certain means `of controlling or adjusting the position of thesaid link for the purpose of cuttingoff at various points in the stroke of the piston; and it further consists in certain means of effecting the connection of a throttle valve with the aforesaid means of adjusting the position of the link for the purpose of bringing the saipl valve `into operation when the resistance 'to the motion `of the en ine is such, that, to regulate by the `cut-o i alone, it would require the steam to be cut off within a certain distance fromV the commencement of the stroke andthrowing it out of operation when the resistance is above that point.

To enable others skilled in the art to make and use my invention, I will proceed to describe4 its construction and operation.

The drawing represents my invention rapplied in`connection with a sliding cut-off valve riding against the back of the main slide valve, forithe reason that I` prefer to use that systemof valves. t i t A, isfthebed-plate, of the engine; B, the cylinder; C, the piston rod; D, the connect--` ing` rod; E,;thecrank, and` F, the crank shaft. t t l G, is the `valve chest; H, the main valve; and I, the maineccentric fast on the crank shaft and connected by its rod I', with the stem H, of the main valve;

All the above mentioned parts are of well known construction.

J, is the sliding cuto1valve applied to work against the back of the main valve in the manner coininonto valves of its class. J", isthe stem ofsaid valvefworking through a stuffingbox inthe valve chest and furnished outside of the chest' with a wrist a, for the connection ofthe slotted link K, with whichtlie rods In, and M,of"the two cut-off eccentrics L, M, are. connected. These eccentrics are so arranged upon the' shaft relatively to the maineccentric that L, `by directconnection withv the wrist/a,

would effect the cutting off ofthe steam at the earliest pointin thestroke of the piston that is desired, and that M, bya similar direct connection would permit the steam tofollow throughout the greatest length of stroke that is desired. The eccentric L, is connected with the link IQby `a joint pin Z, nearly opposite to the` lower endiof its arc formed slot` o, andthe Yeccentric ,con-

`nects with the said link bya joint pin m,

nearly opposite to the upperend of the said t slot, and the said slot"receives`the wrist-jo, which should be itted with a box toj work in the said slot.. By bringing the linkfto the position in which the pinZ, is opp to the wrist a, the cutting off is eifecte` the earliest point in the stroke, and by bi ing it to the position in which the is opposite to the wrist a, the steam is ca t to follow the piston to the farthestp nt and hence by shifting the link between it two positions, the combined action of the two eccentrics will effect the cut oilI atfanv intermediate point more or less distantfrotn j e e those points 'in the-'strokeaccording asthe. U studs Z, or m, are more or `less distant `from the wrist a. Thelink is suspended from a pin o, ina'rocker N, which is caused by the i movement given to the `link by `the. eccene trics, to haveI a vibrating movement on the pin d, which, while the speed of theengine is uniform, is perfectly stationary, but which is made capable of being raisedand lowered under the control of a governor or other device to raise and lower the link for the pur-v pose of regulating the speed of the engine. Various provisions may be made for raising and lowering the said pin, but that which I use is as follows: O, P, is a toggle, one arm O, of which is arranged to swing on a fixed pin e, arranged below the pin cl, and the other arm P, of which has the said pin d, inserted through it. The said pin (Z, is also inserted through a vertically vibrating bridle rod j, working on a fixed pin g. rPhe lower arm O, of the toggle is connected by a rod Q, with a slide R, which is tapped to receive a screw thread on a shaft S, which is arranged to turn but not to move longitudinally in fixed bearings j, y'. By the turning ot' this shaft S, the slide R, is caused to move alongA its screw thread and by this movement of the slide, the joint a, of the toggle O, P, is bent or straightened. The straightening of the toggle raises the pin cl; and the link K, is elevated to the highest position andthe cutting ollip caused to take place at the point nearest the commencement of the stroke when the toggle is quite straight, as shown in red outline in Fig. 3. The bending of the toggle in either direction from this position lowers the pin d, and

-the link as illustrated by the black and blue outlines in Fig. 3, and so causes the steam to follow the piston further. The toggle may be moved from the position shown in blue to that shown in black, or vice versa, by the continued movement of the slide R, in one direction, thus shifting the link from the position by which the steam is caused to follow the piston throughout the greatest portion of its stroke, to the position in which the cut oil takes place nearest the commencement of stroke and bringing it back again to the position in which the steam follows the greatest distance, by one movement. The bridle rod f, prevents the lateral displacement of the pin (Z, and enables the toggle to move the said pin in the desired direction, that is to say, vertically` or thereabout; and it constitutes in fact a guide for the said pin; but by extending the said rod beyond the fixed pin g, on which it vibrates, asl shown at la, it becomes a lever f, 7c, and a weight T, hung 'on the so extended part 7c, is made to counterbalance the weight of the eccentric rods, link K, rocker N, and bridle rod f. The shaft S, may be connected with or have its operation controlled by a governor or be adjustable by hand.

I will now explain the combination of the cut-off gear with the throttle valve, such combination being for the purpose of regulating the engine by the throttle valve when, withthe latter open, the regulation by the cut-off would require steam to be cut 0H within a certain distance of the commencement of the stroke of the piston.

The throttle valve U, represented in the drawing is of the sliding kind applied `close to the valve chest.. V, l/V, is a toggle connecting the stem t, of this valve with a fixed pin a.

X, is a hook for connecting the joint p2,

of the toggle V, W, with a pin p 7 secured in the slide R;.p, is a fixedpin for disengaging al notch 5, in the hook X, from a tooth fl, on the said pin j).

Q, is a spring for causing the tooth l, on the pin f1, to engage in the notch 5', of the hook, as shown in Fig. 2l

The screw S, as the speed increases, is turned in a direction to move the slide R, to the right, and vice versa. lVhen the toggle O, P, is straight as shown in red outline in Fig. 3, and the cut off takes place at the nearest point to the commencement of the stroke, the throttle valve is wide open; but as the slide R, is moved to the left in consequence of a diminution of speed of the engine the toggle O, P, is deflected in the same direction, the hook X, is disconnected from the pin j) by coming in contact with the pin p, and the throttle valve remains disconnected while the link is lowered and steam admitted to follow the piston through a greater portion of the stroke. lVhen the speed of the engine increases while the toggle is deflected to the left, the screw S, is turned in a direction to move the slide R, to the right and straighten the toggle, and the cutting ott' of the steam is caused to take place earlier in the stroke, but the throttle valve remains disconnected from the slide R, till the toggle O, P, is straight and the steam is cut oit at the point nearest the commencement of the stroke, when the pin p, arrives at the bend of the hook X and the notch 5, in the said hook locks with the tooth et, on the said pin; and the continued movement ot' the slide R, while it closes the throttle valve by means of the toggle V, lV, causes the deflection of the toggle O, P, to the right, and so as the throttle valve closes, causes the steam to be admitted to follow the piston through a greater portion of the stroke. When by the diminution o the speed of the engine the sclew S, is again turned in a direction to move the slide R, to the left, the tootln 4, of the pin r, of the slide, still remaining engaged in the notch 5, of the hook X, opens the throttle valve, and at the same time the gradual straightening of the toggle O, P, takes place caus- .ing the cut-oill to operate earlier in the stroke until the toggle is perfectly straight by which time lthe throttle valve is wide open and the hook is disengaged from the pin p, by coming in contact with the pin p, and the cut-ottl is taking place at the earliest point permitted.

The part of the valve gear which operates the cut-0E is not by any means limited in its llO application to the use, in combination with a throttle valve in the manner described, but on the contrary may be applied very advantageously with a riding cut-oft' valve as represented, and in combination with a governor for regulating an engine, without any "connection wththe throttle valve may lcentrics `and link, but inthat case owing to the character of the operation of the valve it cannot bett advantageously used to` regulate under the` control of a governor unless combined Witha throttle valve as described.

F ig. t, exhibits suchmodiications as are necessary to adapt thevalve gear to the use of two short slide valves without aseparate cut-oil, separate va-lvesof any suitable kind (not shown) j being used for eduction. `In this gure Gr, is the cylinder; y Y,`Y, are the valves arranged in separatesteam chests Z, Z. fr, o, are the cylinderports, and s, s, are ports in the valves. jThe valve stems t, t, work ina fixed guide 5, and each has secured y to it a cross head u, which is acted upon on one side for `the purpose of opening the valves by one `of two toes fu, o, on two rockshafts w, @0,3 and on the other side for the purpose of closing the valves by a double toe or cam av, on a rock-shaft y. The rockshaits fw, w, are worked by means of a separate xed eccentric on the crank shaft, and the rockshafty, is worked by the twoeccent trics and link represented in -F igs.` l, 2. and

3, the link being connected with aistud le", in the arm e, ofthe said rock-shaftin the same manner as with the pin a, on the `valve stem represented in those iigures. The two eccentrics vconnected by thelink mayalso be used in a substantiallysimilar manner -in combination `with puppet or otherkindszof` valves `with a suitable system of connections. i I will here remark that the use of `the two eccentrics connected by a link for closing the portsin combination withla separate eccenm tric or other independent means for opening the-ports, differs very materially in its eects `from link motions before used; `for in those the cut-offer expansionisvaried entirelyiby varying the length of stroke of ,thegvalve,`

and this variation ofthe stroke of thevalvel is for reasons known to engineers very objecf tionable but in my link motion even if used in connection with a single slide valve, the

length ofstroke is not changed, `or not mai terially so, the variation being eilected entirely by a variationvin the time ofinove-` ment 'for closing `the ports` `What I claim as my invention and gdesir'ef to secure by Letters Patent, is,

l. The employment of two eccentrics connected by a link for thepurpose of closing tlieports atyariouspoints in the stroke` of the piston` in, combination with independent means of opening the ports for `the `induction i n i of steam, substantially as herein described.`

2. The employment `in combination with the so applied link and its supporting rocker N, of a toggle O, P, so arranged and applied that by a continued movement inone direc,

tion it will carry the link throughout its whole range of motion on` the valve wrist, and back again substantially as `andfor the purpose herein speciiied.

3. The employment, for combining the i throttle valve withthe toggle O, l?, which effects the movement of the cut-oif-link, ofca toothed pin p, a notched hook X, or its equivalent, a stationary pin pi, and a `spring g, the whole combined and operating substantially as herein speciiied. i n

y t 4 J.4 R. ROBINSON.

Witnesses: i y

` LEWIS A. TUCKER,

l JAMnsLAnzD. 

